5R55W Planetary 2002, remanufactured and ready to install. Fits the 5R55W. Ships fast from the USA.
A 2002-and-later Explorer, Mountaineer, Mustang V6 or Thunderbird that whines at cruise, flares into fifth, or came back from a rebuild with erratic shifts may have a burnt overdrive planetary. This is a remanufactured OEM Ford overdrive planet set for the 5R55W and 5R55S, supplied as a complete assembly with the 38-tooth overdrive sun gear. It has been cleaned, inspected for gear wear and scoring, and checked for proper operation, so you are not gambling on a used gearset out of a scrap unit.
The 5R55N, W and S share a basic layout, but Sonnax points out that only a few hard parts interchange between the N and the W/S. The overdrive planetary sits at the front of the geartrain, right behind the pump and the coast clutch drum. Lube for it comes from the front pump through the coast clutch drum, and ATSG's Wayne Colonna reports that it is not unusual to find this planetary destroyed by lack of lubrication. One cause he names is a cooler bypass/thermal valve in the valve body that is slow to send oil to the cooler and lube circuit. Rear lube for the main gearbox is fed from the pressure regulator, so the overdrive planet is often the only gearset that is damaged.
Noise and ratio codes on this family have several causes. Sonnax notes that worn VFS modulator bores in the valve body can starve clutch and servo apply and set gear ratio codes, and that the servo pin bore is often blamed for the same complaint. Work through line pressure and solenoid checks first, using our 5R55 harsh or delayed shift walkthrough and the 5R55W whine and clunk diagnosis guide. If the pan shows heavy metal and the overdrive section has end play or discolored pinions once it is apart, the planet set is finished.
This planet set is listed for 2002-and-later Ford vehicles with the 5R55W or 5R55S, including the Explorer, Mountaineer, Mustang and Thunderbird. The important detail is the sun gear. Sonnax identifies the W with a 24-tooth overdrive sun gear and the S with a 38-tooth overdrive sun gear, and this set comes with the 38-tooth sun. That means an early W unit from a 2002 or 2003 Explorer may need the 24-tooth version instead. Count the teeth on your old overdrive sun gear and match the carrier before you order, or send us your year and VIN and we will confirm it. If yours is the other style, see our 5R55W overdrive planetary listing, and browse everything for this family on the 5R55 transmission parts page.
Check pinion end play and every thrust washer and bearing in the overdrive section, and replace the worn bushings while the unit is apart. Because a lube-starved overdrive planet usually points to a hydraulic cause, do not stop at the gearset. Inspect the cooler bypass/thermal valve and the solenoid regulating valve in the 5R55W valve body, and the flow control valve in the front pump assembly, since ATSG ties repeat failures to those three valves. Seals, frictions and gaskets for the rest of the job come in the 2002-2007 master rebuild kit. Flush the cooler and lines so old debris does not wipe out the new gears, fill with Mercon V, and set the level hot at the fill and check plug.
| Fits | 5R55W 2002 |
| Part type | Planetary |
| Condition | Remanufactured |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
This set includes the 38-tooth overdrive sun gear. Sonnax documents the W with a 24-tooth sun and the S with a 38-tooth sun, so count the teeth on your old sun gear before ordering.
It is listed for 2002-and-later 5R55W and 5R55S applications, but early W units used a 24-tooth sun gear. Match the tooth count and carrier, or send us your year and VIN and we will check it.
Lack of lubrication. ATSG traces it to the lube path from the pump through the coast clutch drum, with a slow cooler bypass/thermal valve as one cause. Fix the hydraulic cause or the new planet can fail the same way.
Thrust washers, bearings and bushings in the overdrive section, plus a full rebuild kit. Inspect the thermal valve, solenoid regulating valve and pump flow control valve as well.
Mercon V. Flush the cooler and lines, refill, and check the level hot at the fill and check plug.
